I did an emerge -u two days ago and Steam's become almost unusable since then. The in-client webkit stuff works though, as does every other Wine app I've tested. But the main GUI just has no text at all, as if it's rendering everything at 0px size. Nobody else seems to have reported bugs about this so I'm posting here in case it's a configuration error.

In the terminal I see hundreds of lines like these when I mouseover stuff, with new ones being added every 1-2 seconds when I'm not doing anything: